Knee flexor muscle fatigue during repeated Nordic hamstring exercise.

Background: Nordic hamstring exercise is an effective method for preventing hamstring strain injury. In this study, we investigated the response of knee flexors regarding increased muscle force and fatigue when the Nordic hamstring exercise was performed repeatedly to further understand how it can prevent hamstring strain injury.

Methods: The Nordic hamstring exercise was performed 10 times by 53 athletes; knee flexor peak tensile force and the respective flexion angle were compared at different phases during this sequence: phase 1, 1 Nordic hamstring exercise force; phase 2, mean value during the 2-4 repetitions; phase 3, mean value during the 5-7 repetitions; and phase 4, mean value during the 8-10 repetitions.

Age-specific neuromuscular interaction during elderly habitual running.

Aim: It has been reported that advancing age causes tendons to become more compliant and fascicles length shorter. This could then lead to enhancement of movement efficiency provided that the elderly adults can activate their muscles in the same way as the younger adults (YOUNG) during dynamic movements. This study was designed to examine the age-specific behaviour of the medial gastrocnemius (MG) fascicles and tendinous tissues together with lower-leg muscle activities when the well-trained elderly runners ran on the treadmill at preferred speeds.

Orthostatic influence on heart rate and blood pressure variability in trained persons with tetraplegia.

To examine the orthostatic influence on heart rate and blood pressure variability in persons with tetraplegia playing wheelchair basketball, ten trained persons with tetraplegia, ten untrained persons with tetraplegia, and ten able-bodied participated in this study. Spectrum analysis of the ECG R-R interval and blood-pressure on a beat-by-beat basis during head-up tilt 60 degrees sitting were performed. The ratio of the high frequency to total frequency (HF/TF) in the R-R interval decreased from supine (0.

Leukemia inhibitory factor, glial cell line-derived neurotrophic factor, and their receptor expressions following muscle crush injury.

Using in situ hybridization histochemistry, we characterized the spatiotemporal gene expression patterns of leukemia inhibitory factor (LIF) and glial cell line-derived neurotrophic factor (GDNF), and their receptor components (LIFR, GFR-alpha1, RET) induced in muscle cells, intramuscular nerves, and motoneurons in the regeneration processes of both muscle cells and nerves following muscle contusion. Muscle contusion induced upregulation of GDNF and GFR-alpha1 mRNAs in Schwann cell-like cells in the intramuscular nerves and of LIFR mRNA in damaged muscle cells. LIFR, GFR-alpha1, and RET mRNA expressions in motoneurons were upregulated following muscle contusion.